Shelf unit



FIG. 1 is a front perspective view of a shelf unit showing my new design;

FIG. 2 is a cross sectional view of a support rod;

FIG. 3 is a cross sectional view of a support leg;

FIG. 4 is a rear elevational view thereof; and,

FIG. 5 is a right side elevational view thereof. 

The ornamental design for a shelf unit, as shown and described. 